There should probably be a way of getting to the main site? I think previously the logo did that, but I wouldn't suggest restoring that. How about linking from the text at the top of the page, under 'UK Puzzle Association'?

I've restored clicking the logo as a return link to the main website. As you say, not a perfect solution.
There doesn't appear to be any other standard configuration to modify the header banner.

However, it is possible to fully customise the header banner by getting stuck into the /prosilver/template/overall_header.html
I don't have the time right now to dig into this, so the original logo clicking will have to suffice for now.

But got this error message:
"Illegal use of $_GET. You must use the request class to access input data. Found in /home/ukpuzzl1/public_html/file_download.php on line 3. This error message was generated by deactivated_super_global."